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8 issues to be noted when injection molding PET preforms
Original: Original | Author: DGMF Mold Clamps | Publish Time: 2020-04-10 | 6748 Views | Share:
Because PET macromolecules contain fat groups and have a certain degree of hydrophilicity, the pellets are more sensitive to water at high temperatures. When the moisture content exceeds the limit, the molecular weight of PET decreases during processing, and the products are colored and brittle.

8 issues to be noted when injection molding PET preforms - DGMF Mold Clamps Co.,ltd

1. Plastic processing

Because PET macromolecules contain fat groups and have a certain degree of hydrophilicity, the pellets are more sensitive to water at high temperatures. When the moisture content exceeds the limit, the molecular weight of PET decreases during processing, and the products are colored and brittle.

Therefore, before processing, the materials must be dried, the drying temperature is 150 , more than 4 hours; generally 170 , 3-4 hours. The air shot method can be used to check whether the material is completely dry. The proportion of PET preform recycled materials should not exceed 25%, and the recycled materials should be thoroughly dried.

2. Selection of injection molding machine

Because PET has a short stabilization time after melting point and a higher melting point, an injection system with more temperature control sections and less self-friction heat generation during plasticization needs to be selected, and the actual weight of the product (water-containing mouth material) cannot be less than that of machine injection 2/3 of the amount.